When a company falls victim to a cyberattack, attention usually focuses on the technical vulnerability that was exploited. However, in most cases, the attack began long before that.
Even before attempting to access information systems, attackers often devote a significant amount of time to gathering information about their target. This step relies on exploiting publicly available data on the Internet and falls under what is known as OSINT, short for Open Source Intelligence.
This practice involves analyzing the digital traces left by an organization to better understand its operations, environment, and potential vulnerabilities. In cybersecurity exercises known as Red Team exercises—which simulate realistic attacks against companies to assess their level of protection—this intelligence phase consistently serves as the starting point of the operation.
Understanding the Company’s Technical Environment
Using publicly available information, it is often possible to identify part of an organization’s digital infrastructure. A company’s simple website can reveal its main domain names, which serve as potential entry points into its information system.
By cross-referencing various open sources, it becomes possible to identify certain services accessible via the Internet, or the technological solutions used by the company. This information can then guide intrusion attempts toward the points most likely to be vulnerable.
Web archives, technical information associated with websites, and certain public databases also make it possible to identify resources that are no longer visible today but existed in the past. These traces can sometimes reveal sensitive information or provide useful clues about the organization of the information system.
Confidential information is also sometimes inadvertently made public, for example through code published online or data from compromised databases. These elements can provide attackers with usernames, email addresses, or other information that could facilitate an intrusion.
Exploiting the Organization’s Human Ecosystem
Beyond technical aspects, publicly available information also provides insight into a company’s human environment.
Professional social networks, institutional websites, or organizations’ public communications often make it possible to identify employees, their roles, and their responsibilities. This information can be used to reconstruct a company’s organizational chart, identify key individuals, or understand the interactions between different teams.
This knowledge of the internal context is particularly useful for preparing social engineering attacks, such as targeted phishing. By drawing on recent events, ongoing projects, or professional interactions visible online, an attacker can craft messages that appear perfectly credible to recipients.
In some cases, analyzing employees’ public profiles can also reveal information about the technologies used within the company or the tools employees use on a daily basis.
Observing the Target’s Physical Environment
Publicly available information may also pertain to an organization’s physical environment.
Online mapping services, for example, can be used to identify the buildings occupied by a company, their access points, or even security measures visible from the outside. These elements can help prepare scenarios for physical intrusion as part of attack simulation exercises.
Photographs published online, whether on social media or institutional websites, can also provide insights into the layout of the premises, employee habits, or even certain internal security measures.
Taken in isolation, this information may seem trivial. But when pieced together, it often allows for the construction of a relatively accurate picture of an organization’s environment.
An Often Underestimated Exposure Point
The open-source intelligence phase demonstrates just how much public information can contribute to preparing an attack. Without ever directly interacting with a company’s systems, it is sometimes possible to collect a significant volume of actionable data.
This reality underscores the importance for organizations to better control their digital footprint. Publicly available information—whether from official communications, employee posts, or technical traces left online—can, when cross-referenced, form a detailed map that an attacker can exploit.
Companies must therefore incorporate this dimension into their cybersecurity strategy. Monitoring publicly accessible information, raising employee awareness about sharing data online, and understanding the organization’s digital exposure have become essential priorities.
Because in many cases, the attack does not begin with a technical intrusion. It simply begins with careful observation of what the company has already made publicly available.
